[Patent Publication]
Japanese Patent Laid-Open Publication No. 2000-208806
[Non-Patent Publication]
Dominic Deslandes and Ke Wu, Integrated Microstrip and Rectangular Waveguide in Planar Form, IEEE Microwave and Wireless Component Letters, Vol. 11, No. 2, 2001.
A dielectric waveguide resonator and a dielectric filter composed of a plurality of dielectric waveguide resonators coupled with each other constitute a circuit component having low-loss characteristics in microwave and millimetric-wave bands. A microstrip or coplanar line is widely used as a signal line for printed electronic circuit boards. In order to use a dielectric waveguide resonator as an electronic circuit component, it is required to connect the resonator to a microstrip or coplanar line in a simple structure (manner).
While there have been proposed some connecting structures between a microstrip line and a dielectric waveguide resonator, none of them has practicability in millimetric-wave band in excess of 30 GHz. The reasons for this difficulty include an extremely reduced size of a downsized dielectric waveguide resonator for millimetric-wave band. The previously proposed connecting structure for a dielectric waveguide resonator is designed such that an input/output electrode pattern to be connected to a microstrip line is formed on a part of the resonator. However, when the resonator is designed to comply with the use in millimetric-wave band, it has to be drastically downsized, which leads to considerable difficulty in forming the input/output electrode pattern to be connected to the microstrip line, on the surface of the dielectric substrate. Even if a very fine electrode could be formed on the surface of the dielectric substance, it is practically difficult to assure reliable connection between the fine electrode and a microstrip line, resulting in poor mass-productivity as a key factor against application of the dielectric waveguide resonator to electronic circuits.